I got an email asking about why a swamp cooler would be smoking. Obviously, that is very concerning, and I would suggest you stop using the cooler until you can determine if there is a problem and what it may be.
There aren’t many things in the cooler that would smoke. Certainly the motor, pump and the switch are connected to electricity, but if you are smelling smoke you need to investigate that carefully.
With the volume of air being blown by the cooler, the smoke would have to be significant in order for you to smell it. It may not even be coming from the cooler. The swamp cooler blows outside air into the house. You can certainly smell a neighbor barbecuing if the barbecue is close to your swamp cooler and the conditions are right. The same thing goes if someone is smoking near the cooler and the cooler is blowing a low volume of air. If you have a good sense of smell you can pick up these odors.
With that being said, there is water and electricity in the cooler, and when they mix bad things can happen. I would be cautious and investigate the cooler. It’s a matter of removing a panel and looking inside. If there is a problem inside, it should be pretty evident.